The present invention relates to impact attenuators for vehicles that have left the roadway, and in particular to such attenuators that are well adapted to bring an axially impacting vehicle to a safe stop and to redirect a laterally impacting vehicle that strikes the side of the attenuator.
Carney U.S. Pat. Nos. 4,645,375 and 5,011,326 disclose two stationary impact attenuation systems. Both rely on an array of vertically oriented metal cylinders. In the ""375 patent, compression elements 54 are arranged in selected cylinders transverse to the longitudinal axis of the array. In the ""326 patent, the cylinders are guided in longitudinal movement by cables extending alongside the cylinders on both outer faces of the array. The individual cylinders are guided along the cables by eye-bolts or U-bolts.
A need presently exists for an improved impact attenuator that provides improved redirection for vehicles impacting the side of the barrier, and that is more easily restored to working condition after an impact.
By way of introduction, the impact attenuators described below include a central, elongated structure that is designed to resist lateral deflection. Tubes are mounted on either side of this elongated structure to slide along the structure in an axial impact and to react against the structure and redirect the vehicle in a lateral impact. The tubes are formed of a resilient, self-restoring material such as an elastomer or a high-density, high-molecular-weight polyethylene. Compression elements are mounted in the cylinders, and these compression elements are oriented at an angle of about 60xc2x0 to the longitudinal axis of the array to improve the redirection capabilities of the system.
The foregoing paragraph has been provided by way of general introduction, and it should not be used to narrow the scope of the following claims.